This invention relates generally to a semiconductor processing system and, more specifically, to a semiconductor processing system having a processing chamber and a heat source assembly.
Rapid thermal processing (RTP) systems are employed in semiconductor chip fabrication to create, chemically alter or etch surface structures on semiconductor wafers. One such RTP system, as described in U.S. Pat. No. 5,155,336, includes a semiconductor processing chamber and a lamp head or heat source assembly located on the semiconductor processing chamber.
The semiconductor processing chamber may be fitted with an adapter plate for low pressure operation. The adapter plate includes a lower quartz window, an upper quartz window and a strengthening component which is sandwiched between the lower and upper windows. The strengthening component may be made of stainless steel and comprises two spaced plates and a surrounding ring which jointly define an enclosed volume. A plurality of tubes are welded into through holes in the plates to form light passageways.
A number of infrared lamps are located in the lamp head. During processing, infrared radiation from the lamps radiate through the upper window, the light passageways and the lower window onto a wafer in the processing chamber. In this manner, the wafer is heated to a required processing temperature.
During processing, the pressure within the processing chamber may be at a subatmospheric pressure. The reduced pressure within the semiconductor processing chamber results in a negative pressure on the lower surface of the lower window. The pressure within the enclosed volume defined by the plates and the surrounding ring can be reduced to a pressure which is lower than the pressure within the processing chamber in order to prevent collapse of the lower window and the lower plate. To this end, a port extends through the surrounding ring and is connected to a pump to reduce the pressure within the enclosed volume defined by the spaced plates and the ring.